Undefined property: stdClass::$uid in QuizQuestion->viewCanRevealCorrect()

hi!

There is a missing $uid property that causes incorrect access

Scenario:

1 - Create a simple quiz with any number of questions, for example 1 multichoice.
2 - Do the quiz
3 - Go to my results: node/1/myresults/1

Notice: Undefined property: stdClass::$uid in QuizQuestion->viewCanRevealCorrect() (line 628 of

  public function viewCanRevealCorrect() {
    global $user;
    // permission overrides the hook
    if (user_access('view any quiz question correct response')
     || $user->uid == $this->node->uid) {
      return TRUE;
    }
    $results = module_invoke_all('answers_access', $this->node);
    $may_view_answers = in_array(TRUE, $results);
    return $may_view_answers;
  }

The problem is that the node is not loaded completely (because of performance reasons) and the uid is not beeing pulled from database so the if statement fails.

Attaching patch to solve it, please review!